JPH05301011A - Method for concentrating gaseous hydrogen chloride - Google Patents

Abstract

PURPOSE:To economically and effectively obtain exhaust gas of higher concentration of gaseous hydrogen chloride than introduced gas by introducing gas contg. gaseous hydrogen chloride into an adsober to adsorb hydrogen chloride and making the gas at lower pressure than that when it is introduced to desorb the adsorbed gaseous hydrogen chloride. CONSTITUTION:Gaseous starting material contg. hydrogen chloride is increased in pressure to the prescribed one by a gas compressor 2 through a pipe 1 and delivered to the 1st adsorber 4a of three adsorbers 4a, 4b, 4c through a switching valve 3. In the adsorber 4a which has adsorbed the prescribed quantity of hydrogen chloride and is just before the saturated state, the gaseous starting material is stopped by switching the switching valve 3, and simultaneously, the adsorber is evacuated by a vacuum pump 10 by switching the switching valve 3 to be in a state of reduced pressure to desorb the hydrogen chloride absorbed on an adsorbent is while the adsorbent is regenerated. In the regeneration process, high concentration hydrogen chloride gas as a product is obtained from a discharge opening of the vacuum pump 10 and delivered to the downstream consumption process.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for concentrating hydrogen chloride using a pressure swing adsorption method.

[0002]

2. Description of the Related Art Hydrogen chloride is a very important industrial intermediate material used in many chemical industries, and there are facilities for separating and concentrating hydrogen chloride in various places. Conventional methods for separating hydrogen chloride from a mixed gas containing hydrogen chloride include (1)
Separation method by distillation at high pressure and low temperature, (2) adsorption method by solvent, (3) method of contacting with water and separating as hydrochloric acid,
(4) There is a hydrogen chloride separation method using an activated carbon adsorption tower.
However, the method (1) requires high pressure and low temperature under severe conditions, consumes a large amount of energy, and cannot be said to be economically advantageous. The method (2) has a low hydrogen chloride purity and cannot be used in a process that requires high-purity hydrogen chloride gas. In the method (3), since hydrogen chloride is recovered as hydrochloric acid in an aqueous solution, it has no use in many cases. In the case of (4), high-purity hydrogen chloride gas can be obtained, but the operation becomes complicated because high temperature regeneration of the adsorbent is required. When separating hydrogen chloride from a gas containing hydrogen chloride as described above, there is currently no effective method for economically and efficiently separating hydrogen chloride.

[0003]

DISCLOSURE OF THE INVENTION The present invention provides a method for separating and concentrating hydrogen chloride from a hydrogen chloride-containing gas economically and efficiently without being subject to legal restrictions such as high pressure gas and environmental problems. is there.

[0004]

Means for Solving the Problems A pressure swing adsorption method is often used as a method for separating gas. It is usually used to increase the purity of oxygen and nitrogen and the purity of carbon monoxide and hydrogen. Prior to the investigation, a prior art survey on hydrogen chloride was conducted. As a result, in the adsorption separation of acidic gas (Japanese Patent Laid-Open No. 62-110744), the adsorbent was selected from basic alkali metal compounds and basic alkaline earth metal compounds. There is only an example of separating hydrogen chloride and nitrogen using a complex of at least one selected and a non-zeolitic porous oxide, and separating and concentrating hydrogen chloride from a hydrogen chloride mixed gas containing carbon monoxide. There is no literature or technology on how to do this.

Therefore, the present inventors diligently investigated whether hydrogen chloride containing gas containing carbon monoxide and hydrogen chloride could be separated by pressure swing adsorption, and used zeolite or non-zeolitic porous acidic oxidation as an adsorbent. It was found that hydrogen chloride can be effectively separated by using a substance, activated carbon or molecular sieving carbon, and the present invention has been completed.

That is, according to the present invention, a gas containing hydrogen chloride is introduced into an adsorption tower filled with an adsorbent capable of adsorbing hydrogen chloride to adsorb hydrogen chloride in particular, and thereafter the introduction of the gas is stopped to stop the adsorption. For this reason, a technology is used in which the adsorbent is regenerated while the adsorbent is desorbed by desorbing the adsorbed hydrogen chloride gas by obtaining a gas with a hydrogen chloride concentration higher than that of the introduced gas by setting the pressure lower than when the gas was introduced. The adsorbent thus regenerated is a method of concentrating hydrogen chloride gas that can be used again for the adsorption of hydrogen chloride gas.

Gases containing hydrogen chloride to which the method of the present invention is applied include oxygen, nitrogen, and gases other than hydrogen chloride.
Hydrocarbons such as carbon dioxide, carbon monoxide, hydrogen, argon, methane, etc. may be present, but in order to separate hydrogen chloride from a gas containing them by a pressure swing adsorption method, these gases and an adsorbent are separated. It is necessary to select one having a sufficiently different adsorption affinity than that for hydrogen chloride.

Therefore, as the hydrogen chloride adsorbent used in the present invention, carbonaceous adsorbents such as synthetic and natural zeolites, non-zeolitic porous acidic oxides, activated carbon and molecular sieving carbon are selected. Examples of zeolites include A type, X type, Y type, L type, ZSM type and mordenite. Examples of the non-zeolitic porous acidic oxide include alumina, silica gel, silica-alumina, titania, magnesia and the like. As the activated carbon, fruit shell type, wood type, coal type, petroleum type, peat type or the like can be used as an adsorbent.

Since hydrogen chloride has a stronger affinity for these adsorbents than the above-mentioned gases, if a gas containing hydrogen chloride is introduced into an adsorption tower filled with these adsorbents. Since hydrogen chloride is adsorbed preferentially over other gases, a gas having a low hydrogen chloride concentration can be obtained at the gas outlet side of the adsorption tower, to the extent that it is rarely detected.

The hydrogen chloride concentration of the gas containing hydrogen chloride to be adsorbed on the adsorbent is not particularly limited, but is usually 10 to 95.
The% hydrogen chloride concentration applies. When the hydrogen chloride concentration is low, the adsorption time until the regeneration operation by desorption can be lengthened. The operation pressure for this adsorption operation is higher than that for the subsequent desorption operation for hydrogen chloride. The operating temperature is determined by the type of adsorbent to be filled, the type of gas other than hydrogen chloride contained in the introduced gas, and economic problems.

For example, when silica gel is used as an adsorbent, sufficient hydrogen chloride adsorption can be performed even at around room temperature. On the other hand, in order to prevent the deterioration of the filling material and the deterioration of the material of the equipment, the water content in the raw material gas is preferably low, and 1000 ppm or less is desirable. When the adsorption of hydrogen chloride in the adsorption tower progresses and approaches a saturated state, the supply of the gas containing hydrogen chloride as a raw material to the adsorption tower is stopped. Then, the operating pressure of the adsorption tower is lowered to desorb adsorbed hydrogen chloride and other gases. The operation pressure at this time is set to be equal to or lower than the pressure at the time of adsorption, and it is also effective to set the pressure to be equal to or lower than the atmospheric pressure by a vacuum pump as needed.

The operating temperature is arbitrary, but basically it is economical to set it at the same temperature as during adsorption. Of course, a so-called thermal swing method can be adopted if it is economically effective.

Further, aeration of a small amount of an inert gas, preferably nitrogen gas, during the desorption operation is a preferred mode because the desorption of hydrogen chloride gas from the adsorbent is promoted. This desorption operation makes it possible to obtain a gas having a higher hydrogen chloride concentration than that of the introduced gas, and the adsorbent that has adsorbed hydrogen chloride can be regenerated because it is dehydrochlorinated, and the next adsorption operation is repeated again. be able to.

Next, the state of implementation in a more specific form on an industrial scale will be described. FIG. 1 shows the form.
In FIG. 1, a raw material gas containing hydrogen chloride is sent from a pipe 1 to a gas compressor 2, where the pressure is increased to a predetermined pressure, and after passing through a switching valve 3, among the three adsorption towers 4a, 4b, 4c. Is sent to the first adsorption tower 4a.

Each of the three adsorption towers 4a, 4b, 4c is filled with an adsorbent that preferentially adsorbs the above-mentioned hydrogen chloride, and hydrogen chloride in the raw material gas introduced under pressure is preferential. At the outlet of the adsorption tower 4a, a gas having a low hydrogen chloride content, and sometimes a gas having a hydrogen chloride concentration that is so low as to be almost undetectable (hereinafter referred to as a treated gas) is obtained.

This dehydrochlorinated gas is sent to the blower 7 via the switching valve 5 and the valve 6 and discharged. At this time, in the second adsorption tower 4b, a part of the treated gas discharged from the first adsorption tower 4a passes through the flow rate adjusting mechanism 8 and the switching valve 9 and then flows into the second adsorption tower 4b.
A pressure increasing step is carried out in which the pressure in the column is introduced into the column b and the pressure in the column is increased by the treated gas, and in the third adsorption column 4c, the vacuum pump 10 in the column and the switching valve 11,
A regeneration process is performed in which the adsorbent is connected via 12a and the adsorbent in this tower is regenerated under reduced pressure.

In the adsorption tower 4a which has just adsorbed a predetermined amount of hydrogen chloride and is about to be saturated, the introduction of the raw material gas is stopped by switching the switching valve 3, and the inside of the tower is vacuum pumped by switching the switching valve 13. At 10 the gas is exhausted to a depressurized state, the hydrogen chloride adsorbed by the adsorbent is desorbed, and the adsorbent is regenerated (regeneration step).

In this regeneration step, a gas having a high hydrogen chloride concentration as a product can be obtained from the discharge port of the vacuum pump 10, and the gas containing a high concentration of hydrogen chloride is sent to the downstream consumption step. At this time, in the second adsorption tower 4b, the raw material gas is introduced through the switching valve 14, the treated gas is discharged from the outlet of this tower, is sent to the blower 7 through the switching valve 15 and the valve 6, and is further consumed. Sent to.

In the third adsorption tower 4c, the second adsorption tower 4 is
A part of the processed gas discharged from b is a flow rate adjusting mechanism 8,
A pressurization step is carried out, which is introduced through the switching valve 16 and the pressure in the column is increased by the treated gas.

After that, in the third adsorption tower 4c, the raw material gas is introduced through the switching valve 17, and the treated gas is sent to the blower 7 through the switching valve 18 and the valve 6 and discharged. At the same time, in the first adsorption tower 4a, a part of the treated gas discharged from the third adsorption tower 4c is introduced through the flow rate adjusting mechanism 8 and the switching valve 19, and the pressure in the tower is adjusted to the treated gas. The pressure boosting process which is increased by is carried out.

At this time, in the second adsorption tower 4b, the switching valve 14
The introduction of the raw material gas is stopped by switching the
By switching the switching valve 20, the inside of the tower is evacuated by the vacuum pump 10 to a depressurized state, the hydrogen chloride adsorbed by the adsorbent is desorbed, and the adsorbent is regenerated.

Similarly, by repeating this series of operations alternately for the three adsorption towers 4a, 4b, 4c, hydrogen chloride is separated from the source gas containing hydrogen chloride, and the hydrogen chloride concentration higher than the concentration of hydrogen chloride in the source gas is obtained. A gas having a hydrogen chloride concentration can be continuously obtained.

[0023]

The present invention will be described in more detail with reference to the following examples. Example 1 Silica gel (manufactured by Fuji Davison, composition SiO ₂ : 99.
7%, Fe ₂ O ₃ : 0.008%, Al ₂ O ₃ : 0.02
5, CaO: 0.01 :, Na ₂ O: 0.05) 43 g
A composition gas of hydrogen chloride (90%) and carbon monoxide (10%) was added to a stainless adsorption column filled with 1 at 25 ° C.
Aeration was performed at 200 ml / min for 7 minutes under the conditions of atm. During this period, the gas flowing out of the column was subjected to gas chromatographic analysis to analyze the gas composition.
0 ppm was detected. After aeration is completed, supply of the raw material gas is stopped, and the adsorption column is set to a pressure of 60 mmHg by a vacuum pump.
The hydrogen chloride was desorbed every 0 minutes, and the desorbed gas was analyzed to find that the hydrogen chloride concentration was 99%. When a gas having the same composition as that of the first gas was passed through the adsorption column after the desorption under the same conditions, the hydrogen chloride concentration of the gas flowing out for 7 minutes was 500 ppm.

Example 2 Silica gel (manufactured by Fuji Devison, composition SiO ₂ : 99.
7%, Fe ₂ O ₃ : 0.008%, Al ₂ O ₃ : 0.02
5, CaO: 0.01 :, Na ₂ O: 0.05) 43 g
A composition gas of hydrogen chloride (90%) and carbon monoxide (10%) was added to a stainless steel adsorption column filled with 5 at 25 ° C.
Aeration was carried out at 200 ml / min for 15 minutes under the conditions of atm. During this period, the gas flowing out of the column was subjected to gas chromatographic analysis to analyze the gas composition.
0 ppm was detected. After aeration is completed, supply of the raw material gas is stopped, and the adsorption column is set to a pressure of 60 mmHg by a vacuum pump.
The hydrogen chloride was desorbed every 0 minutes, and the desorbed gas was analyzed to find that the hydrogen chloride concentration was 98%. When a gas having the same composition as that of the first gas was passed through the adsorption column after the desorption under the same conditions, the hydrogen chloride concentration of the gas flowing out for 15 minutes was 500 ppm.

Example 3 Composition of hydrogen chloride (90%), carbon monoxide (5%) and nitrogen (5%) at 60 ° C. in a stainless adsorption column packed with 40 g of synthetic Y-type zeolite (made by ZEOCHEM). Gas of 1 atm is adjusted to 200 ml / min
Aerated for 7 minutes. During this period, the gas flowing out from the column was subjected to gas chromatographic analysis to analyze the gas composition, and 500 ppm of hydrogen chloride gas was detected. After the completion of aeration, supply of the raw material gas is stopped, and the adsorption column is set to 60 with a vacuum pump.
The pressure of mmHg was maintained for 5 minutes to desorb hydrogen chloride gas. When the desorbed gas was analyzed, the hydrogen chloride concentration was 99%
Met. When a gas having the same composition as that of the first gas was passed through the adsorption column after the desorption under the same conditions, the hydrogen chloride concentration of the gas flowing out for 7 minutes was 500 ppm.

Example 4 Hydrogen chloride (90%) at 25 ° C. in an adsorption column made of stainless steel packed with 23 g of activated carbon PCB (made by Toyo Calgon).
・ One gas with the composition of carbon monoxide (5%) and oxygen (5%)
The pressure was adjusted to atm and the mixture was aerated at 200 ml / min for 11 minutes. During this period, the gas flowing out from the column was subjected to gas chromatographic analysis to analyze the gas composition, and 500 ppm of hydrogen chloride gas was detected. After the completion of aeration, supply of the raw material gas is stopped and the adsorption column is moved to 60 mmHg with a vacuum pump.
The hydrogen chloride gas was desorbed at that pressure for 10 minutes, and the desorbed gas was analyzed. As a result, the hydrogen chloride concentration was 99%. When the gas having the same composition as that of the first gas was passed through the adsorption column after the desorption again under the same conditions, the hydrogen chloride concentration of the gas flowing out for 11 minutes was 500 ppm.

Example 6 Hydrogen sulphate (90%), carbon monoxide (5%), carbon dioxide (5%) at 25 ° C. in a stainless steel adsorption column packed with 20 g of molecular sieve carbon MSC (manufactured by Takeda Pharmaceutical Co., Ltd.).
The gas of the composition is adjusted to a pressure of 1 atm and 200 ml /
Aerated for 11 minutes at min. During this period, the gas flowing out from the column was subjected to gas chromatographic analysis to analyze the gas composition, and 500 ppm of hydrogen chloride gas was detected. After completion of the aeration, the supply of the raw material gas was stopped, the pressure of the adsorption column was kept at 60 mmHg for 10 minutes by the vacuum pump, the hydrogen chloride gas was desorbed, and the desorbed gas was analyzed to find that the hydrogen chloride concentration was 99%. When the gas having the same composition as that of the first gas was again passed through the adsorption column after the desorption under the same conditions, the hydrogen chloride concentration of the gas flowing out for 10 minutes was 500 ppm.
Met.

[0028]

INDUSTRIAL APPLICABILITY The present invention provides a method for easily separating and concentrating hydrogen chloride from a gas containing hydrogen chloride by applying the pressure swing adsorption method, and its industrial value is very large. The present invention is a technique for recovering hydrogen chloride gas using an adsorbent, and is a method that is not subject to the regulation of the law dealing with high-pressure gas and does not require regeneration of the solvent.
The present invention is implemented as an auxiliary equipment in equipment using hydrogen chloride.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an installation using a plurality of adsorption towers for carrying out the present invention particularly continuously.

[Explanation of symbols]

1 Raw material gas supply pipe 2 Compressor 4a, 4b, 4c Adsorption tower 6 Valve 7 Blower 8 Flow rate adjusting mechanism 10 Vacuum pump 3, 5, 9, 11, 12a, 12b, 13-20 Switching valve

Claims (6)

[Claims] 1. A gas containing hydrogen chloride is introduced into an adsorption tower filled with an adsorbent capable of adsorbing hydrogen chloride to adsorb hydrogen chloride, and then the introduction of the gas is stopped. A method for concentrating hydrogen chloride gas, which comprises desorbing under pressure to obtain a gas having a hydrogen chloride concentration higher than the hydrogen chloride concentration of the introduced gas and regenerating the adsorbent. 2. The method according to claim 1, wherein the adsorbent capable of adsorbing hydrogen chloride is zeolite. 3. The method according to claim 1, wherein the adsorbent capable of adsorbing hydrogen chloride is a non-zeolitic porous acidic oxide. 4. The method according to claim 1, wherein the adsorbent capable of adsorbing hydrogen chloride is activated carbon. 5. The method according to claim 4, wherein the activated carbon is molecular sieving carbon. 6. At least one introduced gas containing hydrogen chloride.
The method of claim 1 wherein the component is carbon monoxide.